4-[(1R)-2-amino-1-fluoro-1-methyl-2-oxoethyl]phenyl trifluoromethanesulfonate

4-{(1R)-1-fluoro-1-methyl-2-[(methylsulfonyl)amino]-2-oxoethyl}phenyl trifluoromethanesulfonate

2-[2-(4-trifluoromethanesulfonyloxyphenyl)propionylamino]propionic acid methyl ester

(2S)-2-{[(2R)-2-fluoro-2-(4-{[(trifluoromethyl)sulfonyl]oxy}phenyl)propanoyl]amino}propanoic acid